Neuroticism is a personality trait associated with negative mood states, sensitivity to negative information, negative appraisal and vulnerability to psychopathology. Previous studies have associated the sustained processing of negative information (words) with individual differences such as rumination and depression but not with personality. In the current study, we aimed to investigate the relationship between neuroticism and changes in sustained patterns of activity within a brain region implicated in emotional self-evaluation and appraisal, the Medial Prefrontal Cortex (MedPFC), when responding to emotional facial expressions (happy, fearful, and sad). We tested whether higher scores of neuroticism are associated with greater sustained patterns of brain activity in the MedPFC when responding to blocks of negative facial expressions. We found that higher scores of neuroticism were associated with greater sustained MedPFC activity throughout blocks of sad facial expressions, but not fearful or happy facial expressions. Based on the relationship between neuroticism and sensitivity to negative information, the current finding identifies a sustained temporal mechanism to this relationship.